Homogeneous compositions prepared from dimercaptothiadiazoles

ABSTRACT

Compositions which form homogeneous blends with lubricating oils and the like are produced by preparing a mixture of an oil-soluble dispersant (preferably a substantially neutral or acidic carboxylic dispersant) and a dimercaptothiadiazole, preferably 2,5-dimercapto-1,3,4-thiadiazole, usually with a diluent, especially a lubricant base liquid, and heating said mixture above about 100° C. The compositions often contain dimercaptothiadiazole moieties in amounts substantially greater than stoichiometric. They are useful for suppression of copper activity and &#34;lead paint&#34; deposition in lubricants.

This application is a continuation-in part of copending applicationsSer. No. 380,914, filed July 19, 1973, and Ser. No. 459,428, filed Apr.9, 1974 both now abandoned.

This invention relates to new compositions of matter useful as lubricantadditives, especially for the inhibition of copper activity and "leadpaint" deposition in lubricants, and to lubricants containing suchadditives. More particularly, it relates to compositions obtained bypreparing a mixture comprising at least one oil-soluble dispersant andat least one dimercaptothiadiazole and heating said mixture at atemperature above about 100° C. until it is capable of forming ahomogeneous blend with an oleaginous liquid of lubricating viscosity.

Two phenomena sometimes encountered in internal combustion enginelubrication are copper activity and "lead paint" deposition. The firstof these is a tendency of the lubricant to stain copper parts, and itfrequently results from the use as additives of compounds containing"active sulfur" -- that is, sulfur which is highly labile and reactive.The second phenomenon is the deposition on engine surfaces of a thinfilm of finely divided lead-containing material from the lead additivesin the fuel; this problem is not alleviated by ordinary dispersants ordetergents present in the lubricant. Both of these phenomena areundesirable and it is of interest to develop additives for theirsuppression.

It has been known for some time that derivatives ofdimercaptothiadiazoles, especially of 2,5-dimercapto-1,3,4-thiadiazole,are effective additives for the inhibition of copper activity and manypatents have issued on additives containing dimercaptothiadiazolenuclei. In the development of all of these additives, it has beennecessary to find materials which react with the dimercaptothiadiazoleto form oil-soluble products, since the dimercaptothiadiazolesthemselves are not soluble in oil. An example of such an oil-solubleproduct, disclosed in U.S. Pat. No. 3,519,564, is prepared from one moleof hydrazine, two moles of carbon disulfide and about 1-2 equivalents(based on the number of basic nitrogen atoms therein) of an acylatedpolyamine dispersant. Under the alkaline conditions thus prevailing, thehydrazine, carbon disulfide and dispersant react to form a salt of2,5-dimercapto-1,3,4-thiadiazole.

A principal object of the present invention is to provide newcompositions of matter useful as lubricant additives.

A further object is to provide lubricant additives which are effectiveat suppressing sulfur activity and "lead paint" deposition.

A still further object is to provide new oil-soluble compositionscontaining the dimercaptothiadiazole nucleus.

A still further object is to prepare new and useful lubricants forinternal combustion engines and the like.

Other objects will in part be obvious and will in part appearhereinafter.

The present invention is based on the discovery that at temperaturesabove about 100° C., usually about 100°-250° and especially about120-200° , oil-soluble dispersants interact with amounts ofdimercaptothiadiazoles considerably in excess of those expected on thebasis of salt formation of the type disclosed in the aforementioned U.S.Pat. No. 3,519,564. The compositions thus obtained are capable offorming substantially stable homogeneous blends with lubricatingliquids, which compositions contain higher proportions ofdimercaptothiadiazole than those previously prepared and are effectivefor the purposes hereinbefore described.

The first essential starting material for the preparation of thecompositions of this invention is a dimercaptothiadiazole. There arefour such compounds possible, which are named and have structuralformulas as follows: ##STR1## Of these the most readily available, andthe one preferred for the purposes of this invention, is2,5-dimercapto-1,3,4-thiadiazole. This compound will sometimes bereferred to hereinafter as DMTD. However, it is to be understood thatany of the other dimercaptothiadiazoles may be substituted for all or aportion of the DMTD.

DMTD is conveniently prepared by the reaction of one mole of hydrazine,or a hydrazine salt, with two moles of carbon disulfide in an alkalinemedium, followed by acidification. For the preparation of thecompositions of this invention, it is possible to utilize alreadyprepared DMTD or to prepare the DMTD in situ, subsequently adding thedispersant or adding the DMTD to the dispersant as describedhereinafter.

The second essential starting material is an oil-soluble dispersant. Thematerials chiefly contemplated are often known as "ashless dispersants",although, depending on its constitution, the dispersant may uponcombustion yield a non-volatile material such as boric oxide orphosphorus pentoxide; however, it does not ordinarily contain metal andtherefore does not yield a metal-containing ash on combustion.

Oil-soluble dispersants of many types are known in the art and aredescribed in various patents. Any of them are suitable for use inpreparing the compositions of this invention. The following areillustrative:

(1) Reaction products of carboxylic acids (or derivatives thereof)containing at least about 34 and preferably at least about 54 carbonatoms with nitrogen-containing compounds such as amines, organic hydroxycompounds such as phenols and alcohols, and/or basic inorganicmaterials. Examples of these products, referred to herein as "carboxylicdispersants", are described in British Pat. No. 1,306,529 and in manyU.S. patents including the following: U.S. Pat. No. 3,163,603 U.S. Pat.No. 3,184,474 U.S. Pat. No. 3,215,707 U.S. Pat. No. 3,219,666 U.S. Pat.No. 3,271,310 U.S. Pat. No. 3,272,746 U.S. Pat. No. 3,281,357 U.S. Pat.No. 3,306,908 U.S. Pat. No. 3,311,558 U.S. Pat. No. 3,316,177 U.S. Pat.No. 3,340,281 U.S. Pat. No. 3,341,542 U.S. Pat. No. 3,346,493 U.S. Pat.No. 3,351,552 U.S. Pat. No. 3,381,022 U.S. Pat. No. 3,399,141 U.S. Pat.No. 3,415,750 U.S. Pat. No. 3,433,744 U.S. Pat. No. 3,444,170 U.S. Pat.No. 3,448,048 U.S. Pat. No. 3,448,049 U.S. Pat. No. 3,451,933 U.S. Pat.No. 3,454,607 U.S. Pat. No. 3,467,668 U.S. Pat. No. 3,501,405 U.S. Pat.No. 3,522,179 U.S. Pat. No. 3,541,012 U.S. Pat. No. 3,542,678 U.S. Pat.No. 3,542,680 U.S. Pat. No. 3,567,637 U.S. Pat. No. 3,574,101 U.S. Pat.No. 3,576,743 U.S. Pat. No. 3,630,904 U.S. Pat. No. 3,632,510 U.S. Pat.No. 3,632,511 U.S. Pat. No. 3,697,428 U.S. Pat. No. 3,725,441 U.S. Pat.No. Re 26,433. 3,567,637 U.S. Pat. No. 3,271,310 U.S. Pat. No. 3,433,744U.S. Pat. No. 3,574,101 U.S. Pat. No. 3,272,746 U.S. Pat. No. 3,444,170U.S. Pat. No. 3,576,743 U.S. Pat. No. 3,281,357 U.S. Pat. No. 3,448,048U.S. Pat. No. 3,630,904

(2) Reaction products of aliphatic or alicyclic halides containing atleast about 30 carbon atoms with amines, preferably polyalkylenepolyamines. These may be characterized as "amine dispersants" andexamples thereof are described, for example, in the following U.S. Pat.Nos. 3,275,554 3,438,757 3,454,555 3,565,804.

(3) Reaction products of alkyl phenols in which the alkyl group containsat least about 30 carbon atoms with aldehydes (especially formaldehyde)and amines (especially polyalkylene polyamines), which may becharacterized as "Mannich dispersants". The materials described in thefollowing U.S. patents are illustrative: U.S. Pat. Nos. 3,413,3473,697,574 3,725,277 3,725,480 3,726,882.

(4) Products obtained by post-treating the carboxylic, amine or Mannichdispersants with such reagents as urea, thiourea, carbon disulfide,aldehydes, ketones, carboxylic acids, hydrocarbon-substituted succinicanhydrides, nitriles, epoxides, boron compounds, phosphorus compounds orthe like. Exemplary materials of this kind are described in thefollowing U.S. Pat. Nos. 3,036,003 3,087,936 3,200,107 3,216,9363,254,025 3,256,185 3,278,550 3,280,234 3,281,428 3,282,955 3,312,6193,366,569 3,367,943 3,373,111 3,403,102 3,442,808 3,455,831 3,455,8323,493,520 3,502,677 3,513,093 3,533,945 3,539,633 3,573,010 3,579,4503,591,598 3,600,372 3,639,242 3,649,229 3,649,659 3,658,836 3,697,5743,702,757 3,703,536 3,704,308 3,708,522

(5) Interpolymers of oil-solubilizing monomers containing a pendantalkyl group having at lest about 8 carbon atoms, such as decylmethacrylate, vinyl decyl ether or a relatively high molecular weightolefin, with monomers containing polar substituents, e.g., aminoalkylacrylates, aminoalkyl acrylamides or poly-(oxyalkylene)-substitutedalkyl acrylates. These may be characterized as "polymeric dispersants"and examples thereof are disclosed in the following U.S. Pat. Nos.3,329,658 3,449,250 3,519,565 3,666,730 3,687,849 3,702,300

The pertinent disclosures of all of the above-noted patents areincorporated by reference herein.

The carboxylic dispersants are the preferred ones for use in thepreparation of the compositions of this invention. They may be mostconveniently and accurately described in terms of radicals A and Bpresent therein. Radical A is at least one acyl, acyloxy or acylimidoylradical containing at least about 34 carbon atoms. The structures ofthese radicals, as defined by the International Union of Pure andApplied Chemistry, are as follows (R representing a hydrocarbon orsimilar group): ##STR2##

Radical B is preferably at least one radical in which a nitrogen oroxygen atom is attached directly to said radical A, said nitrogen oroxygen atom also being attached to a hydrocarbon radical or substitutedhydrocarbon radical, especially an amino, alkylamino-,polyalkyleneamino-, hydroxy- or alkyleneoxy-substituted hydrocarbonradical. With respect to radical B, the dispersants are convenientlyclassified as "nitrogen-bridged dispersants" and "oxygen-bridgeddispersants" wherein the atom attached directly to radical A is nitrogenor oxygen, respectively.

The nitrogen-bridged dispersants, which will be described first, arethose disclosed (for example) in the above-mentioned U.S. Pat. Nos.3,219,666 and 3,272,746 which also describe a large number of methodsfor their preparation. The nitrogen-containing group therein is derivedfrom compounds characterized by a radical of the structure > NH whereinthe two remaining valences of nitrogen are satisfied by hydrogen, aminoor organic radicals bonded to said nitrogen atom through directcarbon-to-nitrogen linkages. These compounds include aliphatic,aromatic, heterocyclic and carbocyclic amines as well as substitutedureas, thioureas, hydrazines, guanidines, amidines, amides, thioamides,cyanamides and the like.

Especially preferred as nitrogen-containing compounds used in thepreparation of the nitrogen-bridged dispersants are alkylene polyaminesand hydroxyalkyl-substituted alkylene polyamines. The alkylenepolyamines comprise, in general, alkylene amines containing about 10 orless alkylene groups joined through nitrogen atoms. They includeprincipally the ethylene amines, propylene amines, butylene amines andhomologs thereof, and also piperazines and aminoalkyl-substitutedpiperazines. Hydroxyalkyl-substituted derivatives of these alkylenepolyamines are also contemplated for use in preparing thenitrogen-bridged dispersant. Typical examples of suitable amines areethylene diamine, triethylene tetramine, pentaethylene hexamine,propylene diamine, tri-propylene tetramine, di-(trimethylene) triamine,1,4-bis-(2-aminoethyl)piperazine, 1-(2-aminopropyl)piperazine,N-(2-hydroxyethyl)ethylene diamine, 1-(2-hydroxyethyl)piperazine, and2-heptadecyl-1-(2-hydroxyethyl)-imidazoline. Mixtures of these aminesmay also be used.

The preferred amines are the polyethylene polyamines containing from twoto about eight amino groups per molecule. A commercially availablemixture of polyethylene polyamines containing an average of about 3-7amino groups per molecule is particularly suitable.

The acylating agent used for preparing the nitrogen-bridged dispersantis a carboxylic acid-producing compound containing at least about 34 andpreferably at least about 54 carbon atoms. By "carboxylic acid-producingcompound" is meant an acid, anhydride, acid halide, ester, amide, imide,amidine or the like; the acids and anhydrides are preferred.

The acylating agent is usually prepared by the reaction (more fullydescribed hereinafter) of a relatively low molecular weight carboxylicacid-producing compound with a hydrocarbon source containing at leastabout 30 and preferably at least about 50 carbon atoms. The hydrocarbonsource should be substantially saturated, i.e., at least about 95% ofthe total number of carbon-to-carbon covalent linkages should besaturated. It should also be substantially free from pendant groupscontaining more than about six aliphatic carbon atoms. It may be asubstituted hydrocarbon source; by "substituted" is meant sourcescontaining substituents which do not alter significantly their characteror reactivity. Examples are halide, hydroxy, ether, keto, carboxy, ester(especially lower carbalkoxy), amide, nitro, cyano, sulfoxy and sulfoneradicals. In general, not more than three and usually not more than onesuch radical will be present for each 10 carbon atoms.

The preferred hydrocarbon sources are those derived from substantiallysaturated petroleum fractions and olefin polymers, particularly polymersof monoolefins having from 2 to about 30 carbon atoms. Thus, thehydrocarbon source may be derived from a polymer of ethylene, propene,1-butene, isobutene, 1-octene, 3-cyclohexyl-1-butene, 2-butene,3-pentene or the like. Also useful are interpolymers of olefins such asthose illustrated above with other polymerizable olefinic substancessuch as styrene, chloroprene, isoprene , p-methylstyrene, piperylene andthe like. In general, these interpolymers should contain at least about80%, preferably at least about 95%, on a weight basis of units derivedfrom the aliphatic monoolefins.

Another suitable hydrocarbon source comprises saturated aliphatichydrocarbons such as highly refined high molecular weight white oils orsynthetic alkanes.

In many instances, the hydrocarbon source should contan an activatingpolar radical to facilitate its reaction with the low molecular weightacid-producing compound. The preferred activating radicals are halogenatoms, especially chlorine, but other suitable radicals include sulfide,disulfide, nitro, mercaptan, ketone and aldehyde groups.

As already pointed out, the hydrocarbon sources generally contain atleast about 30 and preferably at least about 50 carbon atoms. Among theolefin polymers those having a molecular weight of about 700-5000 arepreferred, although higher polymers having molecular weights from about10,000 to about 100,000 or higher may sometimes be used. Especiallysuitable as hydrocarbon sources are isobutene polymers within theprescribed molecular weight range, and chlorinated derivatives thereof.

Any one of a number of known reactions may be employed for theincorporation of the hydrocarbon source into the acid-producing compoundto provide the required acylating agent. Thus, an alcohol of the desiredmolecular weight may be oxidized with potassium permanganate, nitricacid or a similar oxidizing agent; a halogenated olefin polymer may bereacted with a ketene; an ester of an active hydrogen-containing acid,such as acetoacetic acid, may be converted to its sodium derivative andthe sodium derivative reacted with a halogenated high molecular weighthydrocarbon such as brominated wax or brominated polyisobutene; a highmolecular weight olefin may be ozonized; a methyl ketone of the desiredmolecular weight may be oxidized by means of the haloform reaction; anorganometallic derivative of a halogenated hydrocarbon may be reactedwith carbon dioxide; a halogenated hydrocarbon or olefin polymer may beconverted to a nitrile, which is subsequently hydrolyzed; or an olefinpolymer or its halogenated derivative may undergo an addition reactionwith an unsaturated acid or derivative thereof. This latter reaction ispreferred, especially where the acid-producing compound is maleic acidor anhydride. The resulting product is then a hydrocarbon-substitutedsuccinic acid or derivative thereof. The reaction leading to itsformation involves merely heating the two reactants at about 100°-200°C. The substituted succinic acid or anhydride thus obtained, may, ifdesired, be converted to the corresponding acid halide by reaction withknown halogenating agents such as phosphorus trichloride, phosphoruspentachloride or thionyl chloride.

For the formation of the nitrogen-bridged dispersant, thehydrocarbon-substituted succinic anhydride or acid, or other acylatingagent, and the alkylene polyamine or other nitrogen-containing reagentare heated to a temperature above about 80° C., preferably about100°-250° C. The product thus obtained has predominantly amide, imideand/or amidine linkages (containing acyl or acylimidoyl groups). Theprocess may in some instances be carried out at a temperature below 80°C. to produce a product having predominantly salt linkages (containingacyloxy groups). The use of a diluent such as mineral oil, benzene,toluene, naphtha or the like is often desirable to facilitate control ofthe reaction temperature.

The relative proportions of the acylating agent and the alkylenepolyamine or the like are such that at least about one-half thestoichiometrically equivalent amount of polyamine is used for eachequivalent of acylating agent. In this regard it will be noted that theequivalent weight of the alkylene polyamine is based upon the number ofamine radicals therein, and the equivalent weight of the acylating agentis based on the number of acidic or potentially acidic radicals. (Thus,the equivalent weight of a hydrocarbon-substituted succinic acid oranhydride is one-half its molecular weight.) Although a minimum ofone-half equivalent of polyamine per equivalent of acylating agentshould be used, there does not appear to be an upper limit for theamount of polyamine. If an excess is used, it merely remains in theproduct unreacted without any apparent adverse effects. Ordinarily, nomore than about 2 equivalents of polyamine are used per equivalent ofacylating agent.

Especially preferred for the purposes of this invention aresubstantially neutral or acidic dispersants; that is, dispersants havinga base number less than 7 or an acid number when titrated to abromphenol blue end point. ("Acid number" is the number of milligrams ofpotassium hydroxide required for titration of a 1-gram sample, and "basenumber" is the number of milligrams of potassium hydroxide equivalent tothe amount of acid required for titration of a 1-gram sample.)Nitrogen-bridged dispersants of this type may often be prepared by usingone equivalent or less of polyamine per equivalent of acylating agent.

In an alternative method for producing the nitrogen-bridged dispersant,the alkylene polyamine is first reacted with a low molecular weight,unsaturated carboxylic acid-producing compound such as maleic anhydrideand the resulting intermediate is subsequently reacted with thehydrocarbon source as previously described.

Oxygen-bridged dispersants comprise the esters of the above-describedcarboxylic acids, as described (for example) in the aforementioned U.S.Pat. Nos. 3,381,022 and 3,542,678. As such, they contain acyl or,occasionally, acylimidoyl radicals as radical A. (An oxygen-bridgeddispersant containing an acyloxy radical as radical A would be aperoxide, which is unlikely to be stable under all conditions of use ofthe compositions of this invention.) These esters are preferablyprepared by conventional methods, usually the reaction (frequently inthe presence of an acidic catalyst) of the carboxylic acid-producingcompound with an aliphatic compound such as a monohydric or polyhydricalcohol or with an aromatic compound such as a phenol or naphthol. Thepreferred hydroxy compounds are alcohols containing up to about 40aliphatic carbon atoms. These may be monohydric alcohols such asmethanol, ethanol, isooctanol, dodecanol, cyclohexanol, neopentylalcohol, monomethyl ester of ethylene glycol and the like, or polyhydricalcohols including ethylene glycol, diethylene glycol, dipropyleneglycol, tetramethylene glycol, pentaerythritol, glycerol and the like.Carbohydrates (e.g., sugars, starches, cellulose) are also suitabe asare partially esterfied derivatives of polyhydric alcohols having atleast three hydroxy radicals.

The reaction is usually effected at a temperature above about 100° C.and typically at 150°-300° C. The esters may be neutral or acidic, ormay contain unesterified hydroxy groups, according as the ratio orequivalents of acid-producing compound to hydroxy compound is equal to,greater than or less than 1:1.

As will be apparent, the oxygen-bridged dispersants are normallysubstantially neutral or acidic. They are among the preferreddispersants for the purposes of this invention.

It is possible to prepare mixed oxygen- and nitrogen-bridged dispersantsby reacting the acylating agent simultaneously or, preferably,sequentially with nitrogen-containing and hydroxy reagents such as thosepreviously described. The relative amounts of the nitrogen-containingand hydroxy reagents may be between about 10:1 and 1:10, on anequivalent weight basis. The methods of preparation of the mixed oxygen-and nitrogen-bridged dispersants are generally the same as for theindividual dispersants described, except that two sources of radical Bare used. As previously noted, substantially neutral or acidicdispersants are preferred, and a typical method of producing mixedoxygen- and nitrogen-bridged dispersants of this type (which areespecially preferred) is to react the acylating agent with the hydroxyreagent first and subsequently react the intermediate thus obtained witha suitable nitrogen-containing reagent in an amount to afford asubstantially neutral or acidic product.

Typical carboxylic dispersants suitable for use in preparing thecompositions of this invention are listed in Table I. "Reagent A" and"Reagent B" are, respectively, the sources of radicals A and B aspreviously defined. The dispersants of Examples 1-6, 8, 9, 12 and 14-17are basic; those of the other examples are substantially neutral oracidic.

                                      TABLE 1                                     __________________________________________________________________________                                        Ratio of                                                                             Reaction      Acid or                                                  equivalents,                                                                         temperature,  base                 Example                                                                             Reagent A     Reagent B       A:B    ° C.                                                                          Diluent                                                                              no.                  __________________________________________________________________________    1     Polyisobutenyl (mol. wt.                                                                    Polyethylene amine mixture                                                                    0.48   150    Mineral                                                                              50B                        about 900) succinic an-                                                                     containing about 3-7 amino                                      hydride prepared from                                                                       groups per molecule                                             chlorinated polyisobutene                                               2     Same as Example 1                                                                           Pentaethylene hexamine                                                                        0.41   150    Mineral                                                                              82B                  3     Like Example 1 except                                                                       Pentaethylene hexamine                                                                        0.61   150    Mineral                                                                              130B                       polyisobutene mol. wt.                                                        is about 1050                                                           4     Like Example 1, except                                                                      Diethylene triamine                                                                           1.0    150    Mineral                                                                              19B                        polyisobutene mol. wt. is                                                     about 850                                                               5     Same as Example 4                                                                           Ethylene diamine                                                                              1.0    150    Mineral                                                                              19B                  6     Same as Example 4                                                                           Di-(1,2-propylene)triamine                                                                    1.0    180-190                                                                              Mineral                                                                              --l-                                                                   toluene                     7     Same as Example 4                                                                           N-(2-hydroxyethyl)-                                                                           1.06   150-155                                                                              Mineral                                                                              4il                                      trimethylene diamine                                      8     Tetrapropenyl succinic                                                                      Triethylene tetramine                                                                         1.0    155    Toluene                                                                              60B                        anhydride                                                               9     Same as Example 1                                                                           Same as Example 1                                                                             0.67   150    Mineral oil                 10    Same as Example 1                                                                           Same as Example 1                                                                             1.33   150    Mineral                                                                              6Bl                  11    Like Example 1, except                                                                      Pentaerythritol, followed by                                                                  0.44   150-210                                                                              Mineral                                                                              2Bl                        polyisobutene mol. wt.                                                                      polyethylene amine of Example 1                                 is about 1100 (ratio of equivalents 7.7:1)                              12    Isostearic acid                                                                             Pentaethylene hexamine                                                                        0.8    150    Mineral                                                                              8Bl                  13    Acid produced by reaction                                                                   Ethylene diamine                                                                              2.0    150    Xylene --                         of chlorinated (3.6%Cl)                                                       polyisobutene (mol. wt.                                                       750) with KCN, followed                                                       by hydrolysis                                                           14    Methyl ester produced                                                                       Triethylene tetramine                                                                         1.0    140-220                                                                              --     --                         by reaction of chlorinated                                                    (4.7%Cl)      polyisobutene                                                   (mol. wt. 1000) with methyl                                                   methacrylate                                                            15    Reaction product of sodio-                                                                  Same as Example 1                                                                             0.4    150    Xylene --                         malonic ester with C.sub.75                                                   brominated wax                                                          16    Reaction product of                                                                         Pentaethylene hexamine                                                                        0.8    180-200                                                                              --     --                         chlorinated (4.5%Cl) poly-                                                    isobutene (mol. wt. 850)                                                      with acrylic acid                                                       17    Acid produced by haloform                                                                   Same as Example 1                                                                             0.8    180-210                                                                              --     --                         reaction with methyl                                                          heptacontanyl ketone                                                    18    Same as Example 11                                                                          Pentaerythritol 0.5    150-210                                                                              Mineral                                                                              --l                  19    Like Example 1, except                                                                      Neopentyl glycol                                                                              1.0    240-250                                                                              --     --                         polyisobutene mol. wt.                                                        is about 1000                                                           20    Same as Example 19                                                                          Methanol*       Excess 50-65  Toluene                                                                              --                                                       methanol                                  21    Same as Example 19                                                                          Polyethylene glycol                                                                           2.0    240-250                                                                              --     --                                       (mol. wt. about 600)                                      22    Same as Example 19                                                                          Oleyl alcohol** 1.0    150-173                                                                              Xylene 0                    23    Like Example 16, except                                                                     Sorbitol        0.48   115-205                                                                              Mineral                                                                              --l                        polyisobutene mol. wt.                                                        is about 982                                                            24    Same as Example 23                                                                          Pentaerythritol 1.0    180-205                                                                              --     --                   25    Reaction product of poly-                                                                   Mannitol        0.33   115-205                                                                              Mineral                                                                              --l                        isobutene (mol. wt. 1500)                                                     with chloroacetyl chloride                                              __________________________________________________________________________     *Hydrogen chloride catalyst                                                   p-Toluenesulfonic acid catalyst                                          

The compositions of this invention are formed by preparing a mixture ofDMTD with the dispersant and heating said mixture within the temperaturerange previously recited, for a period of time sufficient to provide aproduct which is capable of forming a homogeneous blend with anoleaginous liquid of lubricating viscosity, usually with a lubricatingoil such as the natural and synthetic lubricants described hereinafter.The mixture will usually also contain an organic liquid diluent whichmay be either polar on non-polar. Suitable polar liquids includealcohols, ketones, esters and the like. As non-polar liquids there maybe used petroleum fractions, ordinarily high-boiling distillates such asmineral oils of lubricating viscosity, as well as naphthas andintermediate fractions (e.g., gas oil, fuel oil or the like). Alsosuitable are aromatic hydrocarbons, especially the higher boiling onessuch as xylene and various minimally volatile alkylaromatic compounds.Halogenated hydrocarbons such as chlorobenzene may also be used.

It is preferred to use the above-described oleaginous liquids oflubricating viscosity as diluents, since this permits the direct use ofthe composition as a lubricant or a concentrate for incorporation inlubricants. Especially suitable are mineral oils of the paraffinic,naphthenic, or mixed paraffinic-naphthenic types and oils derived fromcoal or shale. Also suitable but less preferred are animal and vegetableoils (e.g., castor oil, lard oil) and synthetic lubricating oils. Thelatter include hydrocarbon oils and halo-substituted hydrocarbon oilssuch as polymerized and interpolymerized olefins (e.g., polybutylenes,polypropylenes, propylene-isobutylene copolymers, chlorinatedpolybutylenes, etc.); alkylbenzenes (e.g., dodecylbenzenes,tetradecylbenzenes, dinonylbenzenes, di-(2-ethylhexyl)benzenes, etc.);polyphenyls (e.g., biphenyls, terphenyls, etc.); and the like. Alkyleneoxide polymers and interpolymers and derivatives thereof where theterminal hydroxyl groups have been modified by esterification,etherification, etc., constitute another class of known syntheticlubricating oils. These are exemplified by the oils prepared throughpolymerization of ethylene oxide or propylene oxide, the alkyl and arylethers of these polyoxyalkylene polymers (e.g., methylpolyisopropyleneglycol ether having an average molecular weight of 1000, diphenyl etherof polyethylene glycol having a molecular weight of 500-1000, diethylether of polypropylene glycol having a molecular weight of 1000-1500,etc.) or mono- and polycarboxylic esters thereof, for examples, theacetic acid esters, mixed C₃ -C₈ fatty acid esters, or the C₁₃ Oxo aciddiester of tetraethylene glycol. Another suitable class of syntheticlubricating oils comprises the esters of dicarboxylic acids (e.g.,phthalic acid, succinic acid, maleic acid, azelaic acid, suberic acid,sebacic acid, fumaric acid, adipic acid, linoleic acid dimer, etc.) witha variety of alcohols (e.g., butyl alcohol, hexyl alcohol, dodecylalcohol, 2-ethylhexyl alcohol, etc.). Specific examples of these estersinclude dibutyl adipate, di(2-ethylhexyl) sebacate, di-n-hexyl fumarate,dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctylphthalate, didecyl phthalate, dieicosyl sebacate, the 2-ethylhexyldiester of linoleic acid dimer, the complex ester formed by reacting onemole of sebacic acid with two moles of tetraethylene glycol and twomoles of 2-ethyl-hexanoic acid, and the like. Silicon-based oils such asthe polyalkyl-, polyaryl-, polyalkoxy- or polyaryloxy-siloxane oils andsilicate oils comprise another useful class of synthetic lubricants(e.g., tetraethyl silicate, tetraisopropyl silicate,tetra-(2-ethylhexyl) silicate, tetra-(4-methyl-2-tetraethyl) silicate,tetra-(p-tert-butyl-phenyl) silicate,hexyl-(4-methyl-2-pentoxy)-di-siloxane, poly(methyl)-siloxanes,poly(methylphenyl)-siloxanes, etc.). Other synthetic lubricating oilsinclude liquid esters of phosphorus-containing acids (e.g., tricresylphosphate, trioctyl phosphate, diethyl ester of decane phosphonic acid,etc.), polymeric tetrahydrofurans, and the like.

In a particularly preferred embodiment, the nonpolar organic liquiddiluent is mineral oil of lubricating viscosity. It is alsocontemplated, though not preferred, to use a volatile liquid initiallyand subsequently replace it by mineral oil, with the volatile liquidbeing removed by distillation, vacuum stripping or the like or todissolve the DMTD in a volatile polar liquid such as an alcohol and toadd the resulting solution to the dispersant-oil mixture, removing thevolatile liquid by flash stripping or other evaporation methods.

The relative amounts of dispersant and DMTD may vary widely, as long asa homogeneous product is ultimately obtained. Thus, about 0.1-10 partsby weight of dispersant may be used per part of DMTD. More often, about5-10 parts of dispersant are used per part of DMTD. The product usuallycontains DMTD moieties in amounts substantially greater than thestoichiometric amount based on salt formation. If the dispersant isneutral or acidic there is, of course, no "stoichiometric amount" ofDMTD and any amount thereof in the product is present in excess. If thedispersant is basic, the product usually contains at least about afive-fold excess and may contain a 500-fold or even greater excess ofDMTD moieties, based on the stoichiometric amount.

The precise chemical nature of the compositions of this invention is notknown. In particular, it is not certain whether a chemical reactiontakes place between the DMTD and the dispersant. However, it has beenshown that DMTD may be dispersed to form a homogeneous composition atlower temperatures than those prescribed for the formation of thecompositions of this invention. When the former composition is heated, asolid product precipitates and upon further heating at a highertemperature, it is redispersed to form a stable, homogeneouscomposition. Hydrogen sulfide evolution is noted as the productprecipitates when the temperature is raised. It is believed that theinitial stage in this process is the homogenization of DMTD by thedispersant, and that the DMTD subsequently condenses to form dimers andother oligomers which first precipitate and are then redispersed as thetemperature rises. Since the normal operating temperatures of aninternal combustion engine are higher than the temperature ofprecipitation, the dispersions first formed are not stable enough toserve as lubricant additives, and it is necessary to go through theprecipitation and redispersion steps to form an additive of thisinvention.

The preparation of the compositions of this invention is illustrated bythe following examples. All parts and percentages are by weight. Theweight ratios of dispersant to DMTD referred to are, in each instance,initial ratios. Equivalents of base in the dispersant are calculatedfrom the base number. Equivalents of DMTD are based on an equivalentweight of 75 (one-half the molecular weight).

EXAMPLE 26

Six thousand parts of the product of Example 10 (0.64 equivalent ofbase) is heated to 100° C., and 484 parts of wet DMTD (420 parts on adry basis, or 5.6 equivalents) is added over 15 minutes, with stirring.The mixture is heated at 110°-120° for 6 hours under nitrogen, duringwhich time hydrogen sulfide evolution is noted. Mineral oil, 1200 parts,is added and the mixture is filtered while hot. The filtrate is a 53%solution of the desired product in oil and contains 1.68% nitrogen and2.83% sulfur. The weight ratio of dispersant to DMTD is 8.6.

EXAMPLE 27

DMTD (5.6 equivalents) is prepared by adding 447 parts of carbondisulfide over 23/4 hours to a mixture of 140 parts of hydrazinehydrate, 224 parts of 50% aqueous sodium hydroxide and 1020 parts ofmineral oil, with stirring under nitrogen at 25°-46° C., heating theresulting mixture at 96°-104° C. for about 3 hours, and then cooling to78° C. and acidifying with 280 parts of 50% aqueous sulfuric acid. Theresulting material is heated to 94° C. and 6000 parts of the product ofExample 10 (0.64 equivalent of base) is added over about 1/2 hour at90°-94° C., under nitrogen. The mixture is heated gradually to 150° C.and maintained at that temperature for about 3 hours; it is thenfiltered while hot to yield a 50% solution in mineral oil of the desiredproduct. The solution contains 2.06 % nitrogen and 3.26% sulfur, and theweight ratio of dispersant to DMTD therein is 8.6.

EXAMPLE 28

One thousand parts of the product of Example 1(0.89 equivalent of base)is heated to 95° C., under nitrogen, and 288 parts of wet DMTD (250parts on a dry basis, or 3.33 equivalents) is added over about 20minutes. The mixture is heated to 150° C. and held at that temperaturefor about 5 hours, and is then filtered while hot to yield the desiredproduct, a 59% solution in oil containing 4.61% nitrogen and 9.19%sulfur. The weight ratio of dispersant to DMTD is 2.4.

EXAMPLE 29

Following the procedure of Example 28, a product is prepared from 200parts each of the dispersant of Example 1 (0.18 equivalent of base) andDMTD (2.67 equivalents), and 2000 parts of mineral oil is added. Theproduct (a 20% solution in oil) contains 1.12% nitrogen and 3.48%sulfur, and the weight ratio of dispersant to DMTD is 0.6.

EXAMPLE 30

Following the procedure of Example 28, a product (50% solution in oil)is prepared from 7300 parts of the product of Example 11 (0.26equivalent of base), 588 parts of wet DMTD (510 parts on a dry basis, or6.8 equivalents) and 1250 parts of mineral oil. It contains 1.72%nitrogen and 3.08% sulfur, and the weight ratio of dispersant to DMTD is7.86.

EXAMPLE 31

Following the procedure of Example 28, a product is prepared from 1000parts of the product of Example 11 (0.036 equivalent of base), 241 parts(3.21 equivalents) of DMTD and 310 parts of mineral oil. The product isa 50% solution in mineral oil and contains 2.74% nitrogen and 6.79%sulfur. The ratio of dispersant to DMTD is 2.62.

EXAMPLE 32

Following the procedure of Example 27, DMTD (8.16 equivalents) isprepared from 204 parts of hydrazine hydrate, 324 parts of 50% aqueoussodium hydroxide, 648 parts of carbon disulfide, 1200 parts of mineraloil and 408 parts of 50% aqueous sulfuric acid. It is then reacted with600 parts of the product of Example 11 (0.02 equivalent of base) in thepresence of 600 parts of toluene, and the toluene and water are removedby azeotropic distillation to yield a product (50% solution in mineraloil) containing 1.8% nitrogen and 5.1% sulfur, and having a 5.5:1 ratioof dispersant to DMTD.

EXAMPLE 33

Following the procedure of Example 27, DMTD (5.6 equivalents) isprepared from 140 parts of hydrazine hydrate, 447 parts of carbondisulfide, 224 parts of 50% aqueous sodium hydroxide, 280 parts of 50%aqueous sulfuric acid and 1020 parts of mineral oil. It is then reactedwith 6000 parts of the product of Example 11 (0.22 equivalent of base)to yield a product (50% solution in oil) containing 1.35% nitrogen and2.64% sulfur, and having a weight ratio of dispersant to DMTD of 7.86.

EXAMPLE 34

Hydrazine hydrate, 28 parts, is mixed with 45 parts of 50% aqueoussodium hydroxide and 206 parts of mineral oil, and 102 parts of carbondisulfide is added over 2 hours. An exothermic reaction takes placewhich causes the temperature to rise to 38° C. The mixture is heated to109° C. and maintained at that temperature for 1 hour, during which timehydrogen sulfide evolution is noted. It is then cooled to 88° C. and 88parts of 33% aqueous sulfuric acid is added over 1/2 hour. Thetemperature rises to 90° C. during this addition.

The resulting slurry (1.12 equivalents of DMTD) is added to 1209 parts(0.043 equivalent of base) of the dispersant of Example 11. Volatilematerials are removed by vacuum stripping at 150° C. and the remainingmixture is heated for 3 hours at that temperature. The residue isfiltered while hot and the filtrate is the desired product containing1.43% nitrogen and 2.90% sulfur, and having a weight ratio of dispersantto DMTD of 7.86.

EXAMPLE 35

A mixture of 1000 parts of the dispersant of Example 11 (0.036equivalent of base) and 170 parts of mineral oil is heated to 70° C.,and a solution of 70 parts (0.93 equivalent) of DMTD in 865 parts ofisopropyl alcohol is added over about 1/2 hour, with stirring. Heatingat 70° C. is continued as the isopropyl alcohol is stripped undervacuum, yielding a homogeneous mixture. This mixture is gradually heatedto 155° C.; during the heating, a solid precipitates and a samplethereof is removed and analyzed. Elemental analysis indicates that it isan oligomer of DMTD, principally a dimer.

As heating continues above 140° C., the solid is gradually solubilizedto yield a homogeneous product again. This product is the desiredmaterial (50% solution in oil) having a dispersant to DMTD ratio of7.86:1.

As previously mentioned, the compositions of this invention areprincipally useful for the inhibition of copper activity and "leadpaint" deposition in lubricants. They may also be used as extremepressure agents and corrosion inhibitors for copper-lead bearings. Theycan be employed in a variety of lubricating compositions based ondiverse oils of lubricating viscosity, including the natural andsynthetic lubricating oils and mixtures thereof disclosed hereinabove assuitable oleaginous diluents. The lubricating compositions contemplatedinclude principally crankcase lubricating oils for spark-ignited andcompression-ignited internal combustion engines including automobile andtruck engines, two-cycle engine lubricants, aviation piston engines,marine and railroad diesel engines, and the like. However, automatictransmission fluids, transaxle lubricants, gear lubricants,metal-working lubricants, hydraulic fluids, and other lubricating oiland grease compositions can benefit from the incorporation of thepresent compositions.

In general, about 0.05-20.0 parts (by weight) of the composition of thisinvention is dissolved in 100 parts of oil to produce a satisfactorylubricant. The invention also contemplates the use of other additives incombination with the products of this invention. Such additives include,for example, detergents and dispersants of the ash-containing or ashlesstype, oxidation inhibiting agents, pour point depressing agents, extremepressure agents, color stabilizers and anti-foam agents.

The ash-containing detergents are exemplified by oil-soluble neutral andbasic salts of alkali or alkaline earth metals with sulfonic acids,carboxylic acids, or organic phosphorus acids characterized by at leastone direct carbon-to-phosphorus linkage such as those prepared by thetreatment of an olefin polymer (e.g., polyisobutene having a molecularweight of 1000) with a phosphorizing agent such as phosphorustrichloride, phosphorus heptasulfide, phosphorus pentasulfide,phosphorus trichloride and sulfur, white phosphorus and a sulfur halide,or phosphorothioic chloride. The most commonly used salts of such acidsare those of sodium, potassium, lithium, calcium, magnesium, strontiumand barium.

The term "basic salt" is used to designate metal salts wherein the metalis present in stoichiometrically larger amounts than the organic acidradical. The commonly employed methods for preparing the basic saltsinvolve heating a mineral oil solution of an acid with a stoichiometricexcess of a metal neutralizing agent such as the metal oxide, hydroxide,carbonate, bicarbonate, or sulfide at a temperature above 50° C. andfiltering the resulting mass. The use of a "promoter" in theneutralization step to aid the incorporation of a large excess of metallikewise is known. Examples of compounds useful as the promoter includephenolic substances such as phenol, naphthol, alkyl-phenol, thiophenol,sulfurized alkylphenol, and condensation products of formaldehyde with aphenolic substance; alcohols such as methanol, 2-propanol, octylalcohol, cellosolve, carbitol, ethylene glycol, stearyl alcohol, andcyclohexyl alcohol; and amines such as aniline, phenylenediamine,phenothiazine, phenyl-β-naphthylamine, and dodecylamine. A particularlyeffective method for preparing the basic salts comprises mixing an acidwith an excess of a basic alkaline earth metal neutralizing agent, aphenolic promoter compound, and a small amount of water and carbonatingthe mixture at an elevated temperature such as 60-200° C.

Ashless detergents and dispersants are illustrated hereinabove.

Extreme pressure agents and corrosion and oxidation inhibiting agentsare exemplified by chlorinated aliphatic hydrocarbons such aschlorinated wax; organic sulfides and polysulfides such as benzyldisulfide, bis(chlorobenzyl) disulfide, dibutyl tetrasulfide, sulfurizedmethyl ester of oleic acid, sulfurized alkylphenol, sulfurizeddipentene, and sulfurized terpene; phosphosulfurized hydrocarbons suchas the reaction product of a phosphorus sulfide with turpentine ormethyl oleate; phosphorus esters including principally dihydrocarbon andtrihydrocarbon phosphites such as dibutyl phosphite, diheptyl phosphite,dicyclohexyl phosphite, pentyl phenyl phosphite, dipentyl phenylphosphite, tridecyl phosphite, distearyl phosphite, dimethyl naphthylphosphite, oleyl 4-pentylphenyl phosphite, polypropylene (molecularweight 500)-substituted phenyl phosphite, diisobutyl-substituted phenylphosphite; metal thiocarbamates, such as zinc dioctyldithiocarbamate,and barium heptylphenyl dithiocarbamate; Group II metalphosphorodithioates such as zinc dicyclohexylphosphorodithioate, zincdioctylphosphorodithioate, barium di(heptylphenyl)phosphorodithioate,cadmium dinonylphosphorodithioate, and the zinc salt of aphosphorodithioic acid produced by the reaction of phosphoruspentasulfide with an equimolar mixture of isopropyl alcohol and n-hexylalcohol.

It is possible to form the lubricants of this invention by dissolvingthe various additives, or oil solutions thereof, directly in a mineraloil. However, it is generally more convenient and is preferred toprepare additive concentrates comprising a diluent (typically mineraloil) and one or more of the desired additives, the latter comprising upto about 90% by weight of the concentrate, and to dissolve theseconcentrates in mineral oil to form the final lubricating composition.

Typical lubricating compositions according to this invention are listedin Tables II and III. All amounts listed, except those for mineral oil,are exclusive of oil present as diluent.

                                      TABLE II                                    __________________________________________________________________________                                Parts by weight                                   Ingredient                                                                           Lubricant            A  B  C  D                                        __________________________________________________________________________    SAE 30 mineral oil base     93.01                                                                            -- 93.81                                                                            --                                       SAE 10W-30 mineral oil base -- 92.74                                                                            -- --                                       SAE 10W-40 mineral oil base -- -- -- 86.82                                    SAE 10W-50 mineral oil base -- -- -- --                                       Product of Example 26       -- -- -- 10.00                                    Product of Example 30       -- 2.10                                                                             -- --                                       Product of Example 33       -- -- 2.12                                                                             --                                       Product of Example 34       2.14                                                                             -- -- --                                       Basic calcium petroleum sulfonate                                                                         -- 0.74                                                                             0.40                                                                             --                                       Basic magnesium petroleum sulphonate                                                                      0.15                                                                             -- -- --                                       Dispersant of Example 10    -- 0.06                                                                             -- 0.10                                     Dispersant of Example 11    1.73                                                                             1.16                                                                             -- --                                       Tetrapropenyl succinic acid anhydride                                                                     0.17                                                                             -- 0.21                                                                             --                                       Sulfurized reaction product of butadiene and butyl acrylate                                               0.65                                                                             0.49                                                                             0.39                                                                             --                                       Sulfurized mixture of soybean oil, tall oil acid and                          C.sub.12-20 α-olefins 1.64                                                                             -- -- --                                       Zinc isooctylphosphorodithioate                                                                           -- -- -- --                                       Zinc salt of mixture of isobutyl- and amylphos-                                                           -- 0.83                                                                             -- --                                       phorodithioic acids                                                           Reaction product of zinc 4-methyl-sec-amylphosphoro-                          dithioate with propylene oxide                                                                            -- -- 0.95                                                                             --                                       Hindered phenol antioxidant 0.33                                                                             -- -- --                                       Polyethoxylated octylphenol 0.18                                                                             -- 0.23                                                                             --                                       Poly-(isodecyl acrylate)    -- 1.88                                                                             -- 3.08                                     Silicone anti-foam agent    0.006                                                                            0.004                                                                            0.006                                                                            0.004                                    __________________________________________________________________________

                                      TABLE III                                   __________________________________________________________________________                                   Parts by weight                                Ingredient               Lubricant                                                                           E  F  G  H  J  K                               __________________________________________________________________________    SAE mineral oil base           -- 93.93                                                                            94.68                                                                            -- -- --                              SAE 10W-40 mineral oil base     89.93                                                                           -- --  87.20                                                                            87.64                                                                            90.36                          Product of Example 26          -- -- -- -- -- 1.00                            Product of Example 32          -- -- -- 2.13                                                                             -- --                              Product of Example 33          -- -- -- -- 2.13                                                                             --                              Product of Example 34          2.16                                                                             2.12                                                                             0.53                                                                             -- -- --                              Basic magnesium petroleum sulfonate                                                                          -- 0.45                                                                             0.14                                                                             -- -- --                              Dispersant of Example 10       0.11                                                                             -- -- 0.11                                                                             0.11                                                                             0.11                            Dispersant of Example 11       -- 1.89                                                                             2.52                                                                             -- -- --                              Dispersant of Example 18       1.98                                                                             -- -- 2.39                                                                             2.39                                                                             --                              Reaction product of 1 equivalent of polyisobutenyl                            succinic anhydride with 2 equivalents of poly-                                ethylene polyamine mixture, further reacted with                              boric acid                     -- -- 0.37                                                                             -- -- --                              Reaction product of polyisobutenyl acrylic acid                               with pentaethylene hexamine    -- -- -- 0.94                                                                             0.94                                                                             0.95                            Tetrapropenyl succinic anhydride                                                                             0.64                                                                             0.21                                                                             -- -- -- --                              Tetrapropenyl succinic acid    -- -- 0.17                                                                             -- 0.34                                                                             --                              Lithium polyisobutenyl succinate                                                                             -- -- -- 1.73                                                                             0.95                                                                             2.90                            Sulfurized reaction product of butadiene and                                  butyl acrylate                 -- 0.39                                                                             0.39                                                                             1.33                                                                             1.33                                                                             1.33                            Zinc isooctylphosphorodithioate                                                                              -- -- 1.02                                                                             -- -- --                              Zinc salt of mixture of isobutyl- and primary                                 amylphosphorodithioic acids    -- 0.78                                                                             -- -- -- --                              Reaction product of phosphorized hydroxypropyl                                4-methyl-sec-amylphosphorodithioic acid with                                  C.sub.11-14 tertiary alkyl primary amine mixture                                                             -- -- -- 0.58                                                                             0.58                                                                             --                              Hindered phenol antioxidant    -- -- -- 0.49                                                                             0.49                                                                             0.25                            Polyethoxylated octylphenol    -- 0.23                                                                             0.18                                                                             -- -- --                              Poly-(isodecyl acrylate)       -- -- -- 3.10                                                                             3.10                                                                             3.10                            Silicone anti-foam agent       0.004                                                                            0.006                                                                            0.006                                                                            0.004                                                                            0.004                                                                            0.004                           __________________________________________________________________________

What is claimed is:
 1. A composition obtained by preparing a mixturecomprising at least one ashless dispersant soluble in a lubricating oiland at least one dimercaptothiadiazole and heating said mixture at about100°-250° C. until it is capable of forming a homogeneous blend with anoleaginous liquid of lubricating viscosity; about 0.1-10 parts by weightof said dispersant being present per part of said dimercaptothiadiazole.2. A composition according to claim 1 wherein the amount ofdimercaptothiadiazole is substantially greater than the stoichiometricamount based on formation of a salt thereof with said dispersant.
 3. Acomposition according to claim 2 wherein the dimercaptothiadiazole is2,5-dimercapto-1,3,4-thiadiazole.
 4. A composition according to claim 3wherein the mixture also contains said oleaginous liquid of lubricatingviscosity.
 5. A composition according to claim 4 wherein the dispersantis selected from the group consisting of carboxylic dispersants, aminedispersants, Mannich dispersants and polymeric dispersants.
 6. Acomposition according to claim 5 wherein the dispersant is a carboxylicdispersant characterized by the presence within its molecular structureof(A) at least one acyl, acyloxy or acylimidoyl radical containing atleast about 30 carbon atoms, and (B) at least one radical in which anitrogen or oxygen atom is attached directly to said radical A, saidnitrogen or oxygen atom also being attached to a hydrocarbon orsubstituted hydrocarbon radical.
 7. A composition according to claim 6wherein the oleaginous liquid is a mineral oil.
 8. A compositionaccording to claim 7 wherein the dispersant has a base number less than7 or an acid number when titrated to a bromphenol blue end point, hassaid radicals A and B connected through linkages selected from the groupconsisting of amide, imide, amidine, amine salt and ester linkages, andis prepared by the reaction of a substantially saturated succinic acid,anhydride, acid halide, ester, amide, imide or amidine containing ahydrocarbon or substituted hydrocarbon radical with at least one of analcohol and an alkylene polyamine.
 9. A composition according to claim 8wherein the dispersant is a mixed oxygen- and nitrogen-bridgeddispersant prepared by sequentially reacting a succinic acid ,anhydride, acid halide, ester, amide, imide or amidine having ahydrocarbon substituent which contains at least about 50 carbon atomswith at least one alcohol and at least one alkylene polyamine.
 10. Acomposition according to claim 9 wherein the hydrocarbon substituent onthe succinic acid, anhydride, acid halide, ester, amide, imide oramidine is a polyisobutenyl substituent.
 11. A lubricating compositioncomprising a major amount of a lubricating oil and a minor amount,suitable to inhibit copper activity and "lead paint" deposition, of acomposition according to claim
 1. 12. A lubricating compositioncomprising a major amount of a lubricating oil and a minor amount,suitable to inhibit copper activity and "lead paint" deposition, of acomposition according to claim
 3. 13. A lubricating compositioncomprising a major amount of a lubricating oil and a minor amount,suitable to inhibit copper activity and "lead paint" deposition, of acomposition accordingto claim
 7. 14. A lubricating compositioncomprising a major amount of a lubricating oil and a minor amount,suitable to inhibit copper activity and "lead paint" deposition, of acomposition according to claim
 8. 15. A lubricating compositioncomprising a major amount of a lubricating oil and a minor amount,suitable to inhibit copper activity and "lead paint" deposition, of acomposition according to claim
 10. 16. A composition obtained bypreparing a mixture comprising:2,5-dimercapto-1,3,4-thiadiazole; amineral oil; and a dispersant which is soluble in said mineral oil andwhich has a base number less than 7 or an acid number when titrated to abromphenol blue end point, said dispersant being prepared bysequentially reacting a polyisobutenyl-substituted succinic acid inwhich the polyisobutenyl substituent contains at least about 50 carbonatoms with pentaerythritol and a polyethylene polyamine containing about3-7 amino groups per molecule; and heating said mixture at about100°-250° C. until it forms a homogeneous blend; about 0.1°-10 parts byweight of said dispersant being present per part of2,5-dimercapto-1,3,4-thiadiazole.
 17. A lubricating compositioncomprising a major amount of a lubricating oil and about 0.05-20.0 partsby weight, per 100 parts of said lubricating oil, of a compositionaccording to clam 16.